The present invention is generally related to sensing methods and systems. The present invention is additionally related to sensors utilized in automotive and mechanical applications. The present invention is also related to magnetoresistors and Wheatstone bridge circuit configurations. The present invention is additionally related to angular position sensing methods and systems thereof.
Various sensors are known in the magnetic-effect sensing arts. Examples of common magnetic-effect sensors include Hall effect and magnetoresistive technologies. Such magnetic sensors can generally respond to a change in the magnetic field as influenced by the presence or absence of a ferromagnetic target object of a designed shape passing by the sensory field of the magnetic-effect sensor. The sensor can then provide an electrical output, which can be further modified as necessary by subsequent electronics to yield sensing and control information. The subsequent electronics may be located either onboard or outboard of the sensor package.
Many automotive electronic systems make use of position sensors. When position sensors for automotive electronic systems were originally conceived and developed, such sensors were primarily utilized for the determination of clutch pedal and shift lever positions in automobile transmission applications. Reasonably accurate linear position sensing was required to identify the positions of the clutch pedal and the shift lever, using electrical signals from a non-contacting sensor approach. For example, in automated manual transmission applications, two sensors may be required to sense the shift lever position as it moves in an H-pattern from Reverse to Low to Second to Third gear. For a standard automatic transmission application, where the shift lever moves along a single axis direction, one position sensor may be required to sense whether the shift lever is in one of the gear operating positions (i.e., Reverse, Neutral, Drive, Low) as well as positions between such operating conditions.
Many of the sensors utilized in automotive applications are configured as angular position sensors, which provide feedback to a control unit. Many of these types of sensors and related systems are mechanical in nature and are very sensitive to the wearing of contacts, contact contamination, and so forth. To help solve many of the warranty problems associated with mechanical sensors, designers have searched for non-contacting electrical solutions provided by magnetoresistive and/or Hall-effect technologies, which have attempted to detect variance in a magnetic field. One of the primary problems with this approach is the inability of such systems to accurately detect position. The accuracy requirement of such systems makes it difficult, for example, to use a single Hall element because of the offset and shifts over temperature.
The difficulty with both Hall and magnetoresistive technologies is that a uniform magnetic field is required. With magnetoresistive technologies, the field strength must additionally be strong enough to saturate the elements. To obtain a uniform field, a ring magnet can be utilized with an IC located centrally thereof, or two magnets can face each other such that an IC is located therebetween. Mounting an IC between the magnets in this manner, however, is difficult to achieve.
The present inventors have thus concluded based on the foregoing that a need exists for an improved angular position sensor, which avoids the aforementioned problems and is adaptable to varying position sensing systems regardless of magnet strengths and dimensions.
The following summary of the invention is provided to facilitate an understanding of some of the innovative features unique to the present invention and is not intended to be a full description. A full appreciation of the various aspects of the invention can be gained by taking the entire specification, claims, drawings, and abstract as a whole.
It is, therefore, one aspect of the present invention to provide an improved sensor method and system.
It is another aspect of the present invention to provide for a sensor that can be used in automotive and mechanical applications.
It is yet another aspect of the present invention to provide for an angular positioning sensing apparatus and method thereof.
It is still another aspect of the present invention to provide for an angular position sensing apparatus that utilizes a magnetoresistive-based sensor.
It is also an aspect of the present invention to provide for an angular position sensing apparatus that utilizes a Hall sensor.
The aforementioned aspects of the invention and other objectives and advantages can now be achieved as is now summarized. An angular position sensing apparatus and method is disclosed herein. The angular position sensing apparatus includes a rotatable base and two or more magnets located proximate to one another upon the rotatable base. The magnets are generally magnetized parallel and opposite to one another to create a uniform magnetic field thereof. Additionally, a sensor can be located external to the two magnets, such that the sensor comes into contact with the uniform magnetic field to sense a change in angular position associated with the rotatable base.
The sensor can be mounted on a printed circuit board (PCB), which is also located external to the magnets. Such a sensor can be configured as, for example, a Hall sensor or a magnetoresistive sensor. If the sensor is configured as a magnetoresistive sensor, such a magnetoresistive sensor can also include a plurality of magnetoresistors arranged within a magnetoresistive bridge circuit. Alternatively, such a magnetoresistive sensor can include two magnetoresistive bridge circuits integrated with one another in a Wheatstone bridge configuration, wherein each of the magnetoresistive bridge circuits comprises four magnetoresistors. The sensor described herein can be configured as an integrated circuit.